The variety of conditions associated with shipping heavy loads by truck or flat-bed trailer has resulted in an industry practise of the use of multiple individual load binders for each loaded item. These binders are commonly chains or belts which are attached to the truck or trailer bed at one or both ends with the opposite end secured and tightened in place to secure the load.
Variations in chains and belts plus the variety of load shapes, sizes and tie down requirements necessitate as many as 18 or more individual load binders used on a single shipment. Each of these must be securely fastened to the correct tension by the driver and then monitored in the event that the load might shift during transport. Variations in loading as a result of transport make disassembly of the load binders not only difficult but more dangerous than the original assembly and lock down. Adverse conditions and working requirements make the assembly and removal treacherous, particularly from the top of the load. This is particularly so in modern just-in-time conditions where transport time, arrival time and time at the dock unloading are all critical elements for the trucker, the shipper and the recipient.
In each case the strap or chain is normally manually tightened and then secured by an over-center lever or pawl latch. These require considerable force applied by lever arms which have a long stroke. Arranging and securing the binder requires the driver to climb up and over the load several times while working the lever arm in awkward positions. As a result of these multiple locations and the variety of shipping conditions, there is no common automated mechanism to achieve this task. The trucker, the shipment and the customer remain subject to delays and risk.
There are 2 types of trailer beds in common use. In the 1st, the bed is perforated along its long edges with holes adapted to receive load restraining posts and chain or strap attachment ends. In this case, if straps are used, these straps can pass over the trailer edge for securement about a rotating spool which is driven automatically or manually and restrained by a latching pawl. In the 2nd, the trailer bed has attached loops which engage side posts and a surrounding protective strapping. This provides a continuous spacing and rail for chain or strap attachment.
Also in common use are air brakes wherein the work is provided by an industry standard ‘maxi’ air pot braking device referred to herein as a pneumatic cylinder. These pneumatic cylinders work in reverse. The internal piston is driven into the pot by a very strong spring (with as much as 50 tons force). This motion closes the brakes towards a fully stopped position. Compressed air is applied to the cylinder chamber and relieves against the spring pressure to drive the piston outward. With air brakes this compressed air progressively releases the truck braking thereby permitting movement. Conversely, release of the air pressure, or failure of the air system entirely, causes braking by allowing the spring to drive the piston inwards and apply a portion or all of the spring pressure to the brakes. By this it is only with the compressed air pressure in operation that the brakes are released and the truck becomes mobile.
Use of the automatic and/or pneumatic load binders saves time and money in the competitive shipping business where customer requirements and ‘just-in-time’ inventory needs dictate minimum time at the loading dock at just the right moment. This in turn further allows the trucker to increase the number of loads, lower the work requirements per load and greatly increase the safety of the transport both on the loading dock and during transportation. Fewer inspections of binder conditions are required and the trucker can avoid many of the impacts of adverse driving conditions in all kinds of climates.
Examples of prior art binders of the wind-up variety are shown in Williams US published pending application 2007/0048103 published Mar. 1, 2007 and Leggett US published pending application 2007/0269285 published Nov. 22, 2007 both with a ratchet lock.
An example of a direct drive binder is shown in Lasswell U.S. Pat. No. 2,773,700 issued Dec. 11, 1956. This is dependent on maintenance of the hydraulic pressure and motor-pump.
Attempts at pressure relieved spring driven binders are found in Meyers U.S. Pat. No. 3,395,932 issued Aug. 6, 1968, Grau U.S. Pat. No. 3,924,544 issued Dec. 9, 1975 and Neidigk U.S. Pat. No. 4,706,343 issued Nov. 17, 1987. These demonstrate a long and sporadic development period of more than 30 years without success or known practical result beyond rotating spool binders mounted below the trailer bed.
Grau provides a spring loaded binder extending vertically through the load bed in a central location. The stroke is very limited and the binding effect is only operative for a direct vertical connection to a single load item.
Neidigk describes a multi-unit or load independent binder providing spring pressure holding. As far as can be seen from the disclosure the device is independent of the truck and an extra part used, if at all, in a fully exposed position above the bed. No satisfactory lock mechanism is disclosed.
Meyer discloses a binder with air release and spring load. In operation as far as can be understood, Meyer is vertically oriented and completely above the load bed. This requires both a retracted load position and a plurality of specialty parts and mechanisms. Stroking is limited, disclosing a cinder suitable under limited conditions for loads and tie-downs with fixed dimensions and little or no variability. As a result, the load is restricted to an apparently unstable elevated position secured against forward and rotary movement and the Meyers binder is not know to operable in conventional, non-load-specific situations and would be difficult and expensive to manufacture with little utility in long term general use.
The primary binders in use are mechanical wind-up devices mounted below the load bed with or without automatic operation with little or no provision for safe full time binding or quick and safe installation, use or removal.
None of the direct drive or relieved spring prior art devices are known to have reached any substantial commercial use likely due to the to the limited stroke provided by the highly exposed vertical orientation and complex load and use specific structures shown. None of the prior art items provide a simple structure which may be attached and used safely in a multiplicity of locations in both existing and new installations by relatively untrained operatives.